Direct-positive photographic emulsion containing, unfogged, monodispersed silver halide grains having a layered grain structure of specific silver chloride content

US3935014A · kind A · utility

Assignee

• Agfa-Gevaert NV · BE

Inventors

• Sieghart Klotzer · Cologne, DE
• Erik Moisar · Cologne, DE

Key dates

• Filing date: Feb 14, 1974
• Grant date: Jan 27, 1976
• Expiry date: Feb 14, 1994

Classification

• Technology area (CPC G): Physics
• CPC primary: G03C1/48576
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A direct-positive photographic material for producing images by fogging development wherein the photographic material contains an unfogged silver halide emulsion layer. The silver halide grains in the unfogged emulsion have a layered grain structure wherein there is a first phase in which is localized a relatively high silver chloride content of at least 20 mol percent based on the total silver halide content of the grain. A second phase contains from less silver chloride than the first phase down to no silver chloride and the total silver chloride in the grain does not exceed 30 mol percent. The physical position of the first phase in the grain is not critical. The emulsion is either not chemically sensitized or only slightly sensitized. The photographic material and its use includes both producing black and white and colored photographic images and has high sensitivity to light and by fogging development yields pure image whites.